SP3223ECY-L-TR Datasheet, PDF (9/21 Pages) Exar Corporation – Intelligent +3.0V to +5.5V RS-232 Transceivers

DESCRIPTION
The SP3223 is a 2-driver/2-receiver device
ideal for portable or handheld applications.
The SP3223 transceivers meet the EIA/TIA-
232 and ITU-T V.28/V.24 communication
protocols and can be implemented in battery-
powered, portable, or handheld applications
such as notebook or handheld computers.
The SP3223 devices feature Exar's propri-
etary on-board charge pump circuitry that
generates ±5.5V RS-232 voltage levels from
a single +3.0V to +5.5V power supply.
These devices are an ideal choice for power
sensitive designs. Featuring AUTO ON-LINE^®
circuitry, the SP3223 reduces the power sup-
ply drain to a 1µA supply current. In many
portable or handheld applications, an RS-232
cable can be disconnected or a connected
peripheral can be turned off. Under these
conditions, the internal charge pump and
the drivers will be shut down. Otherwise, the
system automatically comes online. This
feature allows design engineers to address
power saving concerns without major design
changes.
THEORY OF OPERATION
The SP3223 series is made up of four basic
circuit blocks:
1. Drivers, 2. Receivers, 3. The Exar pro-
prietary charge pump, and 4. AUTO ON-
LINE^® circuitry.
Drivers
The drivers are inverting level transmitters
that convert TTL or CMOS logic levels to 5.0V
EIA/TIA-232 levels with an inverted sense
relative to the input logic levels. Typically, the
RS-232 output voltage swing is +5.4V with
no load and +5V minimum fully loaded. The
driver outputs are protected against infinite
short-circuits to ground without degrada-
tion in reliability. These drivers comply with
the EIA-TIA-232F and all previous RS-232
versions. Unused driver inputs should be
connected to GND or V_CC.
The drivers can guarantee output data
rates fully loaded with 3kΩ in parallel with
1000pF, (SP3223EU, C_L= 250pF) ensuring
compatibility with PC-to-PC communication
software.
+
C5 0.1µF
2 _C1+
+
C1 0.1µF
4 C1-
5 C2+
+
C2 0.1µF
6 C2-
VCC
19
VCC
SP3223E
V+ ³
V- ⁷
+
C3 0.1µF
C4 0.1µF
+
UART
or
Serial µC
11 T1IN
TTL/CMOS INPUTS ₁₂ T₂IN
15 ^R1^OUT
TTL/CMOS OUTPUTS
10 ^R2^OUT
T₁OUT 17
T₂OUT 8
RS-232
OUTPUTS
R₁IN ₁₆
5KΩ
R₂IN ₉
5KΩ
RS-232
INPUTS
RESET
µP
Supervisor
V_IN
IC
EN
VCC
20 _SHUTDOWN
14 _ONLINE
11 _STATUS
GND
18
Figure 13. Interface Circuitry Controlled by Micropro-
cessor Supervisory Circuit
The slew rate of the driver output on the
E and EB versions is internally limited to a
maximum of 30V/µs in order to meet the EIA
standards (EIARS-232D 2.1.7, Paragraph 5).
The Slew Rate of EU version is not limited
to enable higher speed data transfers. The
transition of the loaded output from HIGH to
LOW also meets the monotonicity require-
ments of the standard.
Figure 14 shows a loopback test circuit used
to test the RS-232 Drivers. Figure 15 shows
the test results where one driver was active
at 250kbps and all drivers are loaded with
an RS-232 receiver in parallel with a 1000pF
capacitor. RS-232 data transmission rate of
120kbps to 1Mbps provide compatibility with
designs in personal computer peripherals
and LAN applications.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • www.exar.com

SP3223E/EB/EU_101_062712